What Causes Discomfort In The Center Of Upper Abdomen Along With Diarrhea?

Yesterday, I started feeling slight pressure/discomfort in the center of my upper abd, then I started having alot of gas and diarrhea. I took some imodium and the diarrhea stopped. However, later that night I started coughing alot and then had projectile vomiting. What do you think caused this?